Compact opto-electronic modules and fabrication methods for such modules

ABSTRACT

Various optoelectronic modules are described and include one or more optoelectronic devices. Each optoelectronic module includes one or more optoelectronic devices. Sidewalls laterally surround each optoelectronic device and can be in direct contact with sides of the optoelectronic device or, in some cases, with an overmold surrounding the optoelectronic device. The sidewalls can be composed, for example, of a vacuum injected material that is non-transparent to light emitted by or detectable by the optoelectronic device. The module also includes a passive optical element. Depending on the implementation, the passive optical element can be on a cover for the module, directly on a top surface of the optoelectronic device, or on an overmold surrounding the optoelectronic device. Methods of fabricating such modules are described as well, and can facilitate manufacturing the modules using wafer-level processes.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.14/917,104, filed on Mar. 7, 2016, which is the National Stage ofInternational Application No. PCT/SG2014/000390, filed on Aug. 20, 2014,which claims the benefit of priority U.S. Application No. 61/903,516,filed on Nov. 13, 2013 and U.S. Application No. 61/876,066, filed onSep. 10, 2013. The disclosure of the prior applications is incorporatedherein by reference.

FIELD OF THE DISCLOSURE

This disclosure relates to compact optoelectronic modules andfabrication methods for such modules.

BACKGROUND

Smartphones and other devices sometimes include miniaturizedoptoelectronic modules such as light modules, sensors or cameras. Lightmodules can include a light emitting element such as a light emittingdiode (LED), an infra-red (IR) LED, an organic LED (OLED), an infra-red(IR) laser or a vertical cavity surface emitting laser (VCSEL) thatemits light through a lens to outside the device. Other modules caninclude a light detecting element. For example, CMOS and CCD imagesensors can be used in primary or front facing cameras. Likewise,proximity sensors and ambient light sensors can include a light sensingelement such as a photodiode. The light emitting and light detectingmodules as well as cameras can be used in various combinations. Thus,for example, a light module such as a flash module can be used incombination with a camera that has an imaging sensor. Light emittingmodules in combination with light detecting modules also can be used forother applications such as gesture recognition or IR illumination.

One challenge when integrating an optoelectronic module into a devicesuch as a smartphone is how to reduce light leakage from the lightsource in the light module, or how to prevent incoming stray light fromimpinging, for example, in the case of sensors or cameras. Althoughvarious techniques can be used to achieve these features, it can bedifficult to do so in a manner than results in very compact modules,which can be particularly important for smart phones and other devicesin which space is at a premium.

SUMMARY

This disclosure describes compact optoelectronic modules and fabricationmethods for such modules. Each optoelectronic module includes one ormore optoelectronic devices. Sidewalls laterally surround eachoptoelectronic device and can be in direct contact with sides of theoptoelectronic device or, in some cases, with an overmold surroundingthe optoelectronic device. The sidewalls can be composed, for example,of a vacuum injected material that is non-transparent to light emittedby or detectable by the optoelectronic device. The module also includesa passive optical element. Depending on the implementation, the passiveoptical element can be on a cover for the module, directly on a topsurface of the optoelectronic device, or on an overmold surrounding theoptoelectronic device.

In one aspect, for example, an optoelectronic module includes anoptoelectronic device mounted on a substrate. Sidewalls of the modulelaterally surround the optoelectronic device and are in direct contactwith sides of the optoelectronic device. The sidewalls can be composed,for example, of a vacuum injected material that is non-transparent tolight emitted by or detectable by the optoelectronic device. The modulealso includes a transparent cover disposed over the optoelectronicdevice. In some implementations, the transparent cover is a passiveoptical element or can has a passive optical element attached to itssurface.

One or more of the following features also are present in someimplementations. For example, the sidewalls of the module can becomposed of a UV or thermally-cured polymer material containing anon-transparent filler material. The transparent cover can be separatedfrom the substrate by the sidewalls. In some implementations, a passiveoptical element (e.g., a lens) is disposed directly on an upper surfaceof the optoelectronic device. In such cases, the passive optical elementalso can serve as a cover for the module itself. In some cases, thenon-transparent material that forms the sidewalls of the module isovermolded on the upper surface of the optoelectronic device. Theovermolded material can define a cavity for the location of the passiveoptical element.

According to another aspect, an optoelectronic module includes anoptoelectronic device and sidewalls laterally surrounding theoptoelectronic device and in direct contact with sides of theoptoelectronic device. The sidewalls can be composed of a material thatis non-transparent to light emitted by or detectable by theoptoelectronic device. A passive optical element is disposed on an uppersurface of the optoelectronic device, and electrically conductivecontacts are on an underside of the optoelectronic device and arrangedto mount the module directly on a printed circuit board of a hostdevice. Thus, the module can be arranged such that the optoelectronicdevice can be mounted directly onto an external printed circuit boardwithout the need for an intervening PCB or other substrate.

In yet a further aspect, an optoelectronic module includes anoptoelectronic device mounted on a substrate and a transparent overmoldlaterally surrounding sides of the optoelectronic device and covering atop surface of the optoelectronic device. The overmold is in directcontact with the optoelectronic device. The module further includes apassive optical element on a top surface of the overmold, and sidewallslaterally surrounding the optoelectronic device and in direct contactwith sides of the overmold. Such implementations can be useful, forexample, where the optoelectronic device itself does not include atransparent cover. Further, the top surface of the overmold can beshaped to accommodate variously-shaped lenses or other passive opticalelements, or to act, for example, as a prism.

Methods of fabricating the modules also are described. Such methods caninclude wafer-level fabrication techniques that allow multipleoptoelectronic modules to be made at the same time. In someimplementations, the methods include one or more replication and/orvacuum injection tools to form various features of the modules.

In some implementations, the modules can be made relatively compact,with a relatively small footprint and/or a small overall height. Suchsmall, compact modules can be particularly advantageous for mobilephones and other devices in which space is at a premium.

Other aspects, features and advantages will be readily apparent from thefollowing detailed description, the accompanying drawings and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of an example of anoptoelectronic module in accordance with the invention.

FIGS. 2-6 illustrate a wafer-level method for fabricating multipleoptoelectronic modules at the same time.

FIGS. 7-11 illustrate a second wafer-level method of fabricatingmultiple optoelectronic modules.

FIG. 12 illustrates a cross-sectional view of another example of anoptoelectronic module in accordance with the invention.

FIG. 13 is a top view of optoelectronic module of FIG. 12.

FIG. 14 is a cross-sectional view of a further example of anoptoelectronic module in accordance with the invention.

FIGS. 15A-15D illustrate a wafer-level method of fabricating multipleoptoelectronic modules as shown in FIG. 14.

FIGS. 16A-16C illustrate further examples of optoelectronic modules inaccordance with the invention.

FIGS. 17A-17G illustrate a wafer-level method of fabricating multipleoptoelectronic modules as shown in FIGS. 16A-16C.

FIGS. 18A and 18B illustrate additional examples of modules according tothe invention.

DETAILED DESCRIPTION

The present disclosure describes various compact optoelectronic modulesthat include non-transparent spacers which serve as sidewalls for themodule. An example of such a module is illustrated in FIG. 1, whichshows a module 20 including an optoelectronic device 22 mounted on aprinted circuit board (PCB) or other substrate 24. Examples of theoptoelectronic device 22 include a light emitting element (e.g., a LED,an IR LED, an OLED, an IR laser or a VCSEL) or a light detecting element(e.g., a photodiode or other light sensor). The light emitting or lightdetecting element can be embedded in or formed on, for example, asemiconductor substrate 26, which also can include other circuitelements (e.g., transistors, resistors, capacitive and inductiveelements) and can be protected by a transparent device cover (e.g., acover glass) 28 over the top of the semiconductor substrate 26.

A transparent module cover 30 composed, for example, of glass, sapphireor a polymer material, is separated from the substrate 24 by a spacer32. The transparent module cover 30 generally is transparent towavelengths of light emitted or detectable by the optoelectronic device22, although it may be surrounded at its sides by non-transparentmaterial 33. The spacer 32 preferably is composed of a non-transparentmaterial, which surrounds the optoelectronic device 22 laterally andserves as sidewalls for the module 20. As illustrated in FIG. 1, thespacer 32 is in direct contact with the sides of the optoelectronicdevice 22, which can result in a highly compact module with a relativelysmall footprint.

In some implementations, attached to one side of the transparent modulecover 30 is an optical element such as a lens or diffuser 34. In theillustrated example of FIG. 1, the optical element 34 is present in aninterior area of the module 20. In some implementations, the opticalelement 34 is formed on the transparent module cover 30 by a replicationtechnique (e.g., such as etching, embossing or molding). In otherimplementations, a molded optical element (e.g., a lens) can be fixed ina frame composed of non-transparent material or can be replicated intosuch a frame. The frame then can be attached to the spacer 32.

The optoelectronic device 22 can be mounted to the PCB substrate 24using flip chip technology. For example, the underside of the device 22can include one or more solder balls or other conductive contacts 38that electrically couple the optoelectronic device 22 to conductive padson the surface of the PCB substrate 24. To provide further stability,the area between the bottom surface of the optoelectronic device 22 andthe top surface of the PCB substrate 24 can be filled with an adhesiveunderfill 42. The PCB substrate 24, in turn, can include platedconductive vias that extend from the conductive pads vertically throughthe substrate 24 and that are coupled to one or more solder balls orother conductive contacts 40 on the exterior side of the substrate 24.The conductive contacts 40 allow the module 20 to be mounted, forexample, on a printed circuit board in a handheld device such as amobile phone, tablet or other consumer electronic device.

The foregoing module can be made relatively compact, with a relativelysmall footprint. For example, in some implementations, the overalldimensions of the module 20 of FIG. 1, can be about 2.0 mm (length)×2.3mm (width)×1.3 mm (height). Such small, compact modules can beparticularly advantageous for mobile phones and other devices in whichspace is at a premium.

Modules such as the one illustrated in FIG. 1 and described above can befabricated, for example, in a wafer-level process such that multiplemodules 20 can be fabricated at the same time. Generally, a wafer refersto a substantially disk- or plate-like shaped item, its extension in onedirection (y-direction or vertical direction) is small with respect toits extension in the other two directions (x- and z- or lateraldirections). On a (non-blank) wafer, multiple similar structures oritems can be arranged, or provided therein, for example, on arectangular or other shaped grid. A wafer can have openings or holes,and in some cases a wafer may be free of material in a predominantportion of its lateral area. In some implementations, the diameter ofthe wafer is between 5 cm and 40 cm, and can be, for example, between 10cm and 31 cm. The wafer may be cylindrical with a diameter, for example,of 2, 4, 6, 8, or 12 inches, one inch being about 2.54 cm. The waferthickness can be, for example, between 0.2 mm and 10 mm, and in somecases, is between 0.4 mm and 6 mm. In some implementations of a waferlevel process, there can be provisions for at least ten modules in eachlateral direction, and in some cases at least thirty or even fifty ormore modules in each lateral direction.

FIGS. 2 through 6 illustrate an example of a wafer-level process forfabricating modules such as the module 20 of FIG. 1. As shown in FIG. 2,multiple optoelectronic devices 22 are mounted on a PCB or other supportwafer 102. In some implementations, an array of devices 22 is mounted(e.g., by pick-and-place equipment) on the PCB wafer 102. An adhesiveunderfill 42 can be used to attach the devices 22 to the PCB wafer 102.Next, as shown in FIG. 3, a vacuum injection PDMS tool 104 is placedover the devices 22 and the PCB wafer 102. A vacuum chuck 106 isprovided below and around the PCB wafer 102 so as to apply a vacuumbetween the vacuum injection tool 104 and the PCB wafer 102.

As shown in the example of FIG. 3, the vacuum injection tool 104 hasspaces 108 that surround each device 22 laterally. Preferably, thespaces 108 extend slightly higher than the top of the devices 22.Non-transparent material 114 can be injected under vacuum through aninlet 110 in the vacuum chuck 106 so that it fills the spaces 108 (seeFIG. 4). A vacuum pump 112 near an outlet of the vacuum chuck 106facilitates flow of the injected material. The non-transparent materialcan be composed, for example, of a flowable polymer material (e.g.,epoxy, acrylate, polyurethane, or silicone) containing a non-transparentfiller (e.g., carbon black, a pigment, an inorganic filler, or a dye).The non-transparent material 114 subsequently is hardened (e.g., by UVor thermal curing). The tool 104 and vacuum chuck then can be removed.The result, as shown in FIG. 5, is that non-transparent walls 114 areformed laterally about the sides of each device 22. The non-transparentwalls 114 are in direct contact with the sides of each device 22.Furthermore, the non-transparent walls 114 extend vertically from theupper surface of the PCB wafer 102 to a point somewhat higher than thetop of the devices 22.

Next, as illustrated in FIG. 6, an optics wafer 116 (sometime referredto as a cover wafer) is attached to the top of the walls 114 such thatthe optics wafer 116 is substantially parallel to the PCB wafer 102. Theresult is a wafer stack. The walls 114 thus serve as spacers thatseparate the PCB wafer 102 from the optics wafer 116.

The optics wafer 116 can be composed, for example, of a PCB materialsuch as G10 or FR4 (which are grade designations assigned toglass-reinforced epoxy laminate materials) with openings that are filledwith transmissive material (e.g., glass or plastic). The optics wafer116 thus has optically transmissive regions 118 separated from oneanother by non-transparent regions 120. Each optically transmissiveregion 118 is disposed directly over a corresponding one of theoptoelectronic devices 22 and serves as a transparent window forincoming or outgoing light of a particular wavelength or range ofwavelengths (i.e., light emitted by or detectable by the device 22). Insome implementations, the width (or diameter) of each transmissiveregion 118 is slightly smaller than the corresponding width (ordiameter) of the devices 22. In addition, in some implementations, apassive optical element (e.g., a lens) 124 is disposed on thedevice-side surface of each transmissive region 118. The lenses 124 canbe formed on the transmissive regions 118, for example, by a replicationtechnique prior to attaching the optics wafer 116 to the spacer walls114. In yet other implementations, a passive optical element (e.g., alens) can be replicated directly into a hole in a non-transparent wafer,which is attached to the spacer 32. In that case, the lens itself alsowould serve as a transparent cover for the module.

After attaching the optics wafer 116 to the spacer walls 114 asdescribed above, the wafer stack can be separated (e.g., by dicing)along lines 126 into multiple modules such as the module 20 of FIG. 1.

In the foregoing fabrication process, the passive optical elements(e.g., lenses 124 in FIG. 6) are formed on an optics wafer 116, which issubsequently attached to the injection molded non-transparent material114 to form a wafer stack. In other implementations, the passive opticalelements (e.g., lenses) can be formed as part of a wafer-level processthat does not require a separate optics wafer as described above.Instead, as explained in greater detail below, the passive opticalelements for the modules are replicated directly on the transparentcover 28 of each device 22. An example of such a process is describedbelow in connection with FIGS. 7-11.

As shown in FIG. 7, multiple optoelectronic devices 22 are mounted on aPCB or other support wafer 102. In some implementations, an array ofdevices 22 is mounted (e.g., by pick-and-place equipment) on the PCBwafer 102. An adhesive underfill 42 can be used to attach the devices 22to the PCB wafer 102. Next, as shown in FIG. 8, a combined replicationand vacuum injection tool 104A is placed over the devices 22 and the PCBwafer 102. A vacuum chuck 106 is provided below and around the PCB wafer102 so as to apply a vacuum between the tool 104A and the PCB wafer 102.

As shown in the example of FIG. 8, the replication and vacuum injectiontool 104A has spaces 108 that surround each device 22 laterally and thatsubsequently are filled, by vacuum injection, with a non-transparentmaterial. In some implementations, the spaces 108 extend slightly higherthan the top of the devices 22, although in other implementations thespaces 108 may be substantially flush with the top surface of thetransparent device cover 28. In addition to the spaces 108 for thevacuum injected material, the tool 104A has optical element replicationsections 202 shaped to correspond to the shape of optical elements(e.g., lenses) that will be formed on the top surface of the devices 22.

To form the replicated optical elements, a replication material (e.g., aliquid, viscous or plastically deformable material) is placed onto theoptical replication sections 202, and the top surfaces of thetransparent device covers 28 are brought into contact with the tool 104Aso that the replication material is pressed between the top surface ofeach transparent device cover 28 and the optical element replicationsections 202. The replication material then is hardened (e.g., by UV orthermal curing) to form replicated optical elements 204 (e.g., lenses)on the surface of the transparent device covers 28 (see FIG. 9).

Next, non-transparent material can be injected under vacuum through aninlet 110 in the vacuum chuck 106 so that it fills the spaces 108 (seeFIG. 10). A vacuum pump 112 near an outlet of the vacuum chuck 106facilitates flow of the injected material. The non-transparent materialcan be composed, for example, of a flowable polymer material (e.g.,epoxy, acrylate, polyurethane, or silicone) containing a non-transparentfiller (e.g., a pigment, inorganic filler, or dye). The non-transparentmaterial subsequently is hardened (e.g., by UV or thermal curing). Thecombined replication and vacuum injection tool 104A and vacuum chuckthen can be removed. The result, as shown in FIG. 11, is thatnon-transparent walls 206 are formed laterally about the sides of eachdevice 22. Here too, the non-transparent walls 206 are in direct contactwith the sides of each device 22. Furthermore, the non-transparent walls206 extend vertically from the upper surface of the PCB wafer 102 to apoint somewhat higher than the top of the devices 22 so as to encircleeach lens 204 laterally.

The mounted devices 22 then can be separated (e.g., by dicing) alonglines 126 into multiple modules such as the module 210 of FIG. 12. Themodule 210 is similar to the module 20 of FIG. 1. However, instead of anoptical element (e.g., lens) 34 on the surface of a transparent modulecover 30 as in FIG. 1, the module 210 of FIG. 12 includes a passiveoptical element (e.g., lens) 34A that is directly on the upper surfaceof the device 22 (i.e., on the upper surface of the transparent devicecover 28). Thus, in this example, the optical element 34A also serves asa transparent cover for the module. The arrangement of the module 210 ofFIG. 12 allows its dimensions (e.g., the height) to be made evensmaller, in some cases, than the module 20 of FIG. 1. As in the module20 of FIG. 1, the non-transparent sidewalls 32 of the module 210 of FIG.12 laterally surround the device 22 and are in direct contact with thesides of the device 22. Furthermore, in the illustrated example, thesidewalls 32 can extend somewhat above the top of the device 22 (i.e.,above the top surface of the transparent cover 28) so as to encircle thereplicated lens 34A and to provide a non-transparent baffle 44 for themodule. The height of the baffle 44 can be adjusted, if needed, bychanging the height of the vertical spaces 108 in the tool 104A (see,e.g., FIG. 8).

As described in the foregoing example of FIGS. 7-11, the same tool 104Ais used to form the replicated lenses 204 and to provide the vacuuminjected sidewalls 206. In other implementations, different tools can beused to perform the replication and vacuum injection processes. Forexample, a first vacuum injection tool can be used to form thenon-transparent walls 206 as described above and then a secondreplication tool can be used to form the optical elements 204. In suchsituations, it can be useful to overmold the vacuum injectednon-transparent material slightly onto the top of the transparent devicecover 28 at its edges. The overmolded section 46 (see FIGS. 12 and 13)at the edges of the transparent device cover 28 can define a cavity 48to facilitate formation of the lens 34A in the proper location duringthe subsequent replication process. The upper portion 212 of the spaces108 in the tool 104A can be shaped to obtain the overmolded section 46during the vacuum injection process (see, e.g., FIGS. 8-11).

The foregoing module can be made relatively compact, with a relativelysmall footprint. For example, in some implementations, the overalldimensions of the module 210 of FIG. 12 can be about 2.0 mm (length)×2.3mm (width)×1.0 mm (height). Such small, compact modules can beparticularly advantageous for mobile phones and other devices in whichspace is at a premium.

In the modules of the foregoing examples (e.g., FIGS. 1 and 12), theoptoelectronic device 22 is mounted to a PCB or other substrate 24. Thesubstrate 24 includes conductive contacts such as solder balls 40 on itsunderside to facilitate mounting the module on a printed circuit board.Thus, in the examples of FIGS. 1 and 12, the PCB substrate 24 forms partof the module. Other implementations, however, are possible in which thefinished module does not include a PCB or other substrate 24. Instead,the module can be fabricated such that the optoelectronic device 22 canbe mounted directly on a printed circuit board that is not part of themodule itself. An example of such a module 310 is illustrated in FIG.14. By omitting the PCB or other substrate 24, the overall height of themodule can be reduced even further.

The module of FIG. 14 can be fabricated, for example, using asacrificial substrate on which the optoelectronic devices are mounted.Following formation of the passive optical elements 34A on the uppersurface of the optoelectronic devices 22 and formation of the walls 32,the sacrificial substrate can be removed. An example of such a processis illustrated in FIGS. 15A-15D.

As shown in FIG. 15A, multiple optoelectronic devices 22 are placed on asacrificial support 312, which in turn may be supported, for example, bya more rigid tape 314. The sacrificial support 312 can be composed, forexample, of a soft adhesive material (e.g., PDMS or a polymer foam) suchthat the solder balls 38 of the optoelectronic devices 22 are at leastpartially embedded in the sacrificial support 312. In otherimplementations, the solder balls 38 can be embedded in a thick filmphotoresist or a dry resist, which serves as the sacrificial support312. In some implementations, an array of devices 22 is mounted (e.g.,by pick-and-place equipment) on the sacrificial support 312. Next, asshown in FIG. 15B, a combined replication and vacuum injection tool 104Ais placed over and around the devices 22. A vacuum chuck 106 is providedbelow and around the rigid support tape 314 so as to apply a vacuumbetween the tool 104A and the support tape 314. As the PDMS tool 104Aand vacuum chuck 106 are applied, the solder balls 38 along the bottomsurface of the optoelectronic devices 22 are pressed into the softmaterial of the sacrificial support 312.

An optical element 204 (e.g., lens) can be replicated on the top surfaceof each optoelectronic device 22 in a manner similar to that describedabove in connection with FIGS. 8-9. Thus, to form the replicated opticalelements, a replication material (e.g., a liquid, viscous or plasticallydeformable material) is placed onto the optical replication sections 202of the tool 104A, and the top surfaces of the transparent device covers28 are brought into contact with the tool 104A so that the replicationmaterial is pressed between the top surface of each transparent devicecover 28 and the optical element replication sections 202. Thereplication material then is hardened (e.g., by UV or thermal curing) toform replicated optical elements 204 (e.g., lenses) on the surface ofthe transparent device covers 28 (see FIG. 15C).

In addition, non-transparent walls 206 can be formed around eachoptoelectronic device 22 in a manner similar to that described above inconnection with FIG. 10. Thus, non-transparent material can be injectedunder vacuum through an inlet 110 in the vacuum chuck 106 so that itfills the spaces 108 (see FIGS. 15B and 15C). A vacuum pump 112 near anoutlet of the vacuum chuck 106 facilitates flow of the injectedmaterial. The non-transparent material can be composed, for example, ofa flowable polymer material (e.g., epoxy, acrylate, polyurethane, orsilicone) containing a non-transparent filler (e.g., a pigment,inorganic filler, or dye). The non-transparent material subsequently ishardened (e.g., by UV or thermal curing).

The combined replication and vacuum injection tool 104A and the vacuumchuck 106 then can be removed. In addition, the modules can be separatedfrom the sacrificial support 312, and the devices 22 can be separatedfrom one another (e.g., by dicing) along lines 126 (see FIG. 15D). Ifthe sacrificial support 312 is composed of a soft adhesive, the modulescan be picked up individually, for example, by vacuum suction. On theother hand, if the sacrificial support 312 is composed of a thick filmphotoresist or a dry film resist, the resist can be removed, forexample, by applying UV radiation. In some implementations, the devices22 can be separated from one another (e.g., by dicing) prior to removingthe sacrificial support 312. The result is that non-transparent walls206 are formed laterally about the sides of each device 22. Here too,the non-transparent walls 206 are in direct contact with the sides andbottom of each optoelectronic device 22. As illustrated in FIG. 14, thesame vacuum injected non-transparent material forms the sidewalls 32 ofthe module 310 and are in direct contact with the sides of theoptoelectronic device 22. Thus, the vacuum injected non-transparentmaterial effectively serves as a housing for the optoelectronic device22. Furthermore, in the illustrated example, the non-transparent walls206 extend vertically from the upper surface of the PCB wafer 102 to apoint somewhat higher than the top of the device 22 so as to encirclethe lens 204 laterally, thereby providing a baffle. In someimplementations, the vacuum injected non-transparent material can beovermolded slightly onto the top of the transparent device cover 28 atits edges as described above in connection with FIGS. 12 and 13.

By forming the lens 34A directly on the top surface of theoptoelectronic device 22 and by forming the module such that the solderballs 38 for the optoelectronic device 22 can be mounted directly ontoan external printed circuit board without the need for an interveningPCB or other substrate, a highly compact module 310 can be obtained. Inparticular, the module 310 can have a relatively small overall height.

In the foregoing implementations of FIGS. 12 and 14, the passive opticalelement (e.g., lens) 34A is formed directly on the upper surface of theoptoelectronic device 22 (e.g., on the transparent cover 28). In someimplementations, however, it can be advantageous to form a transparentovermold 402 over the optoelectronic device 22 and then subsequentlyform the optical element 34A on the surface of the overmold 402 (seeFIG. 16A). The overmold 402, which can be composed, for example, of acurable polymer such as epoxy, thus protects the optoelectronic device22 and serves as a support for the lens or other passive optical element34A. Such implementations can be useful, for example, where theoptoelectronic device 22 itself does not include a transparent cover 28.Further, use of the overmold can obviate the need for a separate opticswafer during fabrication of the module (e.g., optics wafer 116 in FIG.6). The top surface of the overmold 402 can be shaped forvariously-shaped lenses or other passive optical elements. For example,FIG. 16B illustrates an example in which the lens-side surface of theovermold 402A is shaped so as to conform to the shape of the lens 34B.The overmold 402 and lens 34B can be composed of the same or differentmaterials. For example, the overmold 402 can be composed of a materialhaving a first index of refraction, and the lens 34B can be composed ofa second material having a higher index of refraction. In someimplementations, such as shown in FIG. 16C, the surface of the overmold402B on which a passive optical microstructure 34C is formed can beslanted (e.g., shaped like a prism). Implementations like the one ofFIG. 16C can facilitate introducing light deflection and/or beamshaping. Here too the optical microstructure can be composed of the sameor different material as the overmold 402B. Thus, providing atransparent overmold to encapsulate the optoelectronic device 22 canfacilitate incorporating any of a wide range of passive optical elementsinto the module.

The modules of FIGS. 16A-16C can be fabricated, for example, as part ofa wafer-level process in which multiple modules are manufactured at thesame time. An example of such a process is illustrated in FIGS. 17A-17GFor example, as illustrated in FIG. 17A, multiple optoelectronic devices(e.g., light emitting or light detecting devices) are mounted on a PCBor other substrate 24. In some implementations, an array of devices 22is mounted (e.g., by pick-and-place equipment) on the substrate 24.Next, as shown in FIG. 17B, a first PDMS vacuum injection tool 504 isplaced over and around the devices 22. A vacuum chuck 506 is providedbelow and around the substrate 24 so as to apply a vacuum between thefirst tool 504 and the substrate 24. Next, a transparent material (e.g.,an epoxy) is injected under vacuum through an inlet 110 in the vacuumchuck 506 so that it fills spaces 508, whose shape (when viewed fromabove) can be rectangular, circular or some other shape depending on theimplementation. Injection channels 509, as well as a vacuum pump 112near an outlet of the vacuum chuck 506, facilitate flow of the injectedmaterial. The transparent material in the spaces 508 subsequently ishardened (e.g., by UV or thermal curing) to form transparent overmoldregions 510 (see FIG. 17C). To obtain overmold regions having a curvedupper surface as in FIG. 16B or a slanted upper surface as in FIG. 16C,the shape of the spaces 508 defined by the first tool 504 can bemodified appropriately. Following formation of the overmold regions 510by vacuum injection, the first tool 504 and the vacuum chuck 506 areremoved (see FIG. 17C), and the regions corresponding to the vacuumchannels 509 are removed by dicing along lines 512. The resultingstructure is shown in FIG. 17D.

In some cases, instead of forming an overmold 510 over each device 22using the vacuum injection technique described in connection with FIGS.17A-17D, an overmold can be formed over each device 22 by encapsulatingthe devices in a transparent material using a screen printing process.For example, a PCB substrate 24, on which are mounted light emitting orlight detecting devices 22, can be placed in a screen printer.Transparent encapsulation material then is provided by a print screenprocess so as to encapsulate each device 22. After curing theencapsulation material, the screen is released and removed, resulting inmultiple encapsulated devices 22. A PCB wafer 24, including overmoldedor encapsulated devices 22, then can be used, for example, in theprocess of FIGS. 17E-17G, described below.

An optical element 204A (e.g., lens) can be replicated on the topsurface of each overmold region 510 in a manner similar to thatdescribed above in connection with FIGS. 8 and 9. Thus, to form thereplicated optical elements, a replication material (e.g., a liquid,viscous or plastically deformable material) is placed onto the opticalreplication sections 202A of a second combined replication and vacuuminjection tool 504A. See FIG. 17A. The top surfaces of the overmoldregions 510 are brought into contact with the second tool 504A so thatthe replication material is pressed between the top surface of eachovermold region 510 and a corresponding optical element replicationsection 202A. The replication material then is hardened (e.g., by UV orthermal curing) to form replicated optical elements 204A (e.g., lenses)on the surface of the overmold regions 510 (see FIG. 17F). To formoptical elements having a different shape (e.g., such as 34B in FIG. 16Bor 34C in FIG. 16C), the shape of the optical element replicationsections 204A can be modified appropriately.

In addition, non-transparent walls 206A can be formed in a mannersimilar to that described above in connection with FIG. 10. Thus,non-transparent material can be injected under vacuum through the inlet110 in the vacuum chuck 506A so that it fills the spaces 108A (see FIG.17G) surrounding the overmold regions 510. The vacuum pump 112 near theoutlet of the vacuum chuck 506A facilitates flow of the injectedmaterial. The non-transparent material can be composed, for example, ofa flowable polymer material (e.g., epoxy, acrylate, polyurethane, orsilicone) containing a non-transparent filler (e.g., a pigment,inorganic filler, or dye). The non-transparent material subsequently ishardened (e.g., by UV or thermal curing).

The second tool 504A and the vacuum chuck 506A then can be removed, andthe devices 22 can be separated (e.g., by dicing) along lines 126 (seeFIG. 17G). In contrast to the implementations of FIGS. 1, 12 and 14, thenon-transparent walls 206A are not in direct contact with the sides ofeach optoelectronic devices 22. Instead, the non-transparent walls 206Aare in direct contact, respectively, with the sides of the overmoldregions 510.

In the illustrated example of FIG. 17G the dicing lines 126 are locatedsuch that each module includes a pair of side-by-side optoelectronicdevices 22 separated by a non-transparent wall 206A. Thus, the resultingmodules can include multiple optical channels separated from one anotherby a non-transparent wall composed of the same material as the module'souter sidewalls. In some implementations, one of the optoelectronicdevices 22A in the pair can be a light emitting element, whereas thesecond of the optoelectronic devices 22B can be a light detectingelement. Examples of such modules are illustrated in FIGS. 18A and 18B.Furthermore, a first type of passive optical element may be disposedover one of the optoelectronic devices, and a different type of passiveoptical element (or no passive optical element) can be disposed over theother optoelectronic device. Examples of such modules are illustrated inFIGS. 18A and 18B. Other multi-channel modules having differentcombinations of optoelectronic devices, overmold regions and passiveoptical elements can be provided as well. Such modules can be fabricatedusing wafer-level techniques as described above. The areas of the tools504 (see FIG. 17B) and 504A (see FIG. 17E) that define, respectively,the spaces 508 for the vacuum injected overmold regions 510 and thefeatures 202A for the replicated passive optical elements 204A can bemodified appropriately.

In some implementations, each module may contain, for example, only asingle optoelectronic devices 22 (i.e., a single optical channel) asshown in FIGS. 16A-16C. It also is possible to provide each module witha two-dimensional M×N array of optoelectronic devices 22, where both Mand N are two or more. When the module subsequently is mounted, forexample, on a printed circuit board of a host device, underfill materialcan be provided, if desired, to protect the solder balls 38.

As used in this disclosure, the terms “transparent” and non-transparent”are made with reference to wavelength(s) of light in the visible and/ornon-visible portions (e.g., infra-red) of the spectrum emitted by ordetectable by the light emitting or light detecting elements in theoptoelectronic device. Thus, for example, if a particular feature of themodule is non-transparent, the feature is substantially non-transparentto the particular wavelength(s) of light emitted by or detectable by thelight emitting or light detecting elements in the optoelectronic device.The particular feature may, however, be transparent or partiallytransparent with respect to other wavelengths.

The modules described here can be used in a wide range of applications,including, for example, ambient light sensors, proximity sensors, flashmodules and image sensors, as well as others.

Various modifications can be made to the foregoing examples.Accordingly, other implementations are within the scope of the claims.

1. An optoelectronic module comprising: an optoelectronic device mountedon a substrate; sidewalls of the module laterally surrounding theoptoelectronic device and in direct contact with sides of theoptoelectronic device, wherein the sidewalls are composed of a materialthat is non-transparent to light emitted by or detectable by theoptoelectronic device; and a transparent cover disposed over theoptoelectronic device.
 2. The optoelectronic module of claim 1 whereinthe sidewalls are composed of a vacuum injected material.
 3. Theoptoelectronic module of claim 1 wherein the sidewalls are composed of aUV or thermally-cured polymer material containing a non-transparentfiller material.
 4. The optoelectronic module of claim 1 wherein thetransparent cover is separated from the substrate by the sidewalls, themodule further including a passive optical element disposed on atransparent section of the transparent cover for the module.
 5. Theoptoelectronic module of claim 1 wherein the optoelectronic deviceincludes: a light emitting element or a light detecting element; and atransparent device cover over the light emitting element or the lightdetecting element, wherein the transparent device cover is differentfrom the transparent cover disposed over the optoelectronic device. 6.The optoelectronic module of claim 5 including a passive optical elementdisposed directly on the transparent device cover.
 7. The optoelectronicmodule of claim 5 wherein the non-transparent material is overmolded onthe transparent device cover near its edges.
 8. The optoelectronicmodule of claim 1 wherein the transparent cover is a passive opticalelement.
 9. The optoelectronic module of claim 6 wherein the passiveoptical element is a lens.
 10. The optoelectronic module of claim 6further including a baffle laterally surrounding the passive opticalelement, wherein the baffle is composed of the same non-transparentmaterial as the sidewalls of the module.
 11. The optoelectronic moduleof claim 1 further including an adhesive underfill between theoptoelectronic device and the substrate on which it is mounted.
 12. Awafer-level method of fabricating optoelectronic modules, the methodcomprising: providing a support wafer on which are mounted a pluralityof optoelectronic devices; using a vacuum injection technique to providea non-transparent material on sides of each of the optoelectronicdevices; attaching a cover wafer over the optoelectronic devices so asto form a wafer stack, wherein the cover wafer provides a transparentsection over each of the optoelectronic devices; and separating thewafer stack into a plurality of individual optoelectronic modules eachof which includes one of the optoelectronic devices laterally surroundedby sidewalls of the module, the sidewalls being in direct contact withthe sides of the optoelectronic device and being composed of the vacuuminjected material.
 13. The method of claim 12 wherein the vacuuminjected material is substantially non-transparent to light emitted byor detectable by the optoelectronic devices.
 14. The method of claim 12wherein the sidewalls are composed of a UV or thermally-cured polymermaterial containing a non-transparent filler material.
 15. The method ofclaim 12 wherein the cover wafer includes a plurality of passive opticalelements such that a respective one of the passive optical elements isdisposed over each optoelectronic device.
 16. The method of claim 15wherein the passive optical elements are replicated directly on asurface of the cover wafer.
 17. The method of claim 12 includingattaching the cover wafer to the non-transparent material that forms thesidewalls for the modules.
 18. The method of claim 12 wherein using avacuum injection technique to provide a non-transparent material onsides of each of the optoelectronic devices includes: causing anon-transparent material composed of a flowable polymer materialcontaining a non-transparent filler to be provided in spaces of a vacuuminjection tool, wherein the spaces laterally surround the sides of theoptoelectronic devices; and causing the non-transparent material toharden. 19-56. (canceled)